dna

I set the advance at 3500rpm, which was set to 32. So yes the timing was right.

dna

OK - I poured some oil into #5 and re-did compression - no difference

Warship2k15

And yoi have the carb open while testing?

Well if it had changed it would have ment that the rings on #5 were shot.
Since it didnt they could still be bad.
I would put a leak down tester or some pressire on the #5 while at tdc of compression stroke and see if you hear any hissing of leaking air.
you can isolate it with a stethoscope or a chunk of hose to see if you hear it at the intake or exhaust.

Also you might want to check the valve lash on the number 5 with it at tdc of compression.

dna

OK, so made a diy leak down tester. Basically got an old spark plug, plut it into vise, took sledge to porcelean to make hollow, then took spare air hose with quick-fitting on other end. My compressor already had a regulator so set it to 100psi and connected to #5. Sure enough you can hear a constant stream of air, but I couldn't make out where it was. Nothing obvious from the intake or exhaust manifolds - sounded more like inside the engine. Will need to take off valve cover at min to hopefully pin point it.

Speaking of valve covers, I started to remove the one side but without loosening/removing the exhaust manifold I can't get at bolts. Is there a trick to remove the valve cover without removing the exhaust manifold?

I'm hoping at this point it is valve lash on #5. If it is the actual valves, does that mean the head has to come off - or is there any trick to seat them without removing the head?

Thanks

dna

Forgot to get #5 to tdc before introducing air - so ignore above post as tht is why air was escaping. But still need to take off cover anyway - is there an easy way. Also anyone have a good suggestion on how to get to tdc without the cover off - with the cover off I'll be able to see it but with cover off it is not as easy

dereknkathy

1/4 inch drive u joint and 7/16th socket should get the 2 hard to get bolts. Also, fire up your psi tester and turn engine by hand. You will hear diff when valves open and then close. Tdc for 5 is 1/4 turn of crank after timing mark. You could pop dist cap to see it is firing on 6, not 1 at tdc mark, then turn crank 90 degrees.

dna

So by psi tester, you mean to introduce 100psi into cylinder and turn engine manually - what would I be looking/hearing for?

Confused with the distrib cap thing - why would this have anything to do with my low compression on #5? You mention to see if #6 is firing - could this somehow affect or caused #5 issue?

Any suggestions why it would go from running perfect at wot for 10 minutes and then instantly loose 1 cylinder, being that it was not overheated? I don't think it is head gasket being that no other cylinder has the issue. Also don't think it is rings being the wet test didn't make a difference in compression. I'm leaning towards valves on seated - any ideas why it would though go from great to dead within the first 10 minutes of running? Could it be the lash was not set right on #5?

Thanks

1BIGJIM

iTrader: (1)

Your making this too hard. use a remote starter or have someone turn engine over a few clicks at a time. Stick your finger over #5 hole. When air starts to push your finger off the hole your on the compression stoke. You don't have to have it at top dead center. Both valves will be closed.

dna

Gonna remove the valve cover today and do a leak down test. I'll also play a little with the lash and check if possibly debris is stuck between the valve and seat. If I conclude the issue is with valves (not bottom end) I'm gonna start to remove head again. Dumb question - can I re-use any of the gaskets being they are still fairly new? I'm planning to leave the riser on the exhaust manifold and thus only remove the exhaust manifold (so the riser gasket will be OK). But can I reuse the exhaust manifold gasket, intake gasket, and head gasket?

Thanks

phragle

iTrader: (3)

gaskets ARE CHEAP. Motors arent. Catch my drift?? Slow down, think about what your doing and do it right. Your not trying to fix the damn lawn mower so you can get the lawn mowed before it rains this afternoon. Now you tell me why would it die after 10 minutes? think think think, not rush rush rush.